atoms and molcules
-
Upload
mukundapriya -
Category
Science
-
view
51 -
download
3
description
Transcript of atoms and molcules
ATOMS AND MOLECULES
contents
•Laws of Chemical Combination•Law of Conservation of Mass•Law of Constent Proportion
•Atom•Molecule
IntroductionWhat you mean by atom and molecule? Atom: Smallest particle of element May or may not exist independtly May or may not have properties of matter Molecule: Smallest particle of compound Always exist independtly Always posses the properties of matter
Law of chemical combination
• atoms exist in the combined formI. Law of conservation of massII. Law of constent proportion
Law of conservation of mass
• A Lavoisier-father of chemistry• mass can be neither created nor be destroyed
Law of constent proportion
• Joseph Proust: pure chemical compound contain element in definite proportion by mass
ATOM• Atomic symbols:short hand reperesentation for the name
of elementEg:H - hydrogen,Ne – neon
• Atomic mass:mass of an atom of an elementEg:H - 1,Ca - 16
• Atomic mass unit:mass of one twelth of mass of 1 carbon 12 atom
• Average atomic mass:atomic mass of isotopesEg:H-1.008 and it is taken as 1 unit
• Gram atomic mass: atomic mass expressed in gramsEg:C – 12g , N-14g
• Atomic combination: atoms are bonded together by strong forces of attraction and the new species is called molecules.Molecules are of 2 types
I. Homoatomic: same type of atomsII. Heteroatomic: 2 or more types of atoms
• Ions:atom having +ve or –ve chargeI. Cation: +ve charged ionII. Anion: -ve charged ion
MOLECULE• Molecular mass: mass of the molecules of a chemical compound. Expressed in amu Determined by adding the individual atomic massEg:molecular mass of NH3 =atomic mass of N + 3 * atomic mass of H = 14+[3*1] =17 amu
• Gram molecular mass: molecular mass expressed in grams Numericlly equal to molecular mass in amu Eg: I g molecule of H20 =18g
MOLE CONCEPT• 1 Mole = 6.023 * 1023 number of particles• 1 mole of any substance contain avagrado
number[6.023*1023] of particles which have weight equvalent to atomic mass
• Number of moles = total mass molecular mass N= W M
Conclusion
• All elemnts are made up of atom• Atoms have differenr mass and organisation• Electrons,protons,neutrons make atoms• Molecule-2 or more atom combined to form
single species